1. Field of the Invention
The present invention relates to a magnetic tape cassette used for an audio or a video tape recorder, which has a pad for pushing a magnetic tape against guide rollers or guide poles.
2. Discussion of Background
There has been known a magnetic tape cassette of a type that a magnetic tape is wound around reel hubs rotatably supported in the casing. When data recorded in the magnetic tape are to be reproduced, the magnetic tape rewound at a supplying side reel hub runs toward a winding side reel hub while it is guided by guide rollers and/or guide poles arranged in a running path of the magnetic tape. When the magnetic tape is rewound at a winding side reel hub, it is driven in the opposite direction. In this case, the guide poles simply determine the passage of the magnetic tape, and the guide rollers supported in a freely rotatable manner function not only to determine the running path but also to make the running of the magnetic tape smooth. A pad is provided in the casing to push the magnetic tape against the guide rollers and/or the guide poles to remove a loosing state in the magnetic tape when it is driven in the magnetic tape cassette.
The pad 12 is constituted by an elongated thin member disposed near an area of rotation of the winding side reel hub 10 as shown in FIG. 6. The pad 12 has a fitting part 18 with an aperture at an intermediate portion near its one end in which a supporting pin 16 projecting from a casing 14 is inserted. The pad 12 has a pressing part 20 at the other end and an elongated arm 22 at the intermediate portion near the pressing part 20. In FIG. 6, reference numerals 24 and 26 designate guide rollers having a small diameter, a numeral 28 designates a guide roller having a large diameter, a numeral 30 designates the above-mentioned magnetic tape and a numeral 32 designates a front face to close a front opening 34 in the casing 14.
However, in the conventional magnetic tape cassette, when the pad 12 is elastically deformed by a friction casued by the magnetic tape when the tape is driven, the arm 22 of the pad 12 may be bent, whereby it enters in the area of rotation of the reel hub 10. When an accident of the contact of the pad 12 to the reel hub 10 takes place, the rotation of the reel hub 10 is hindered resulting in a fault of running. Further, there arise problems such that the pad 12 is damaged reducing its pressing force and scraped powder is deposited on the magnetic tape 30 to cause a drop-out phenomenon.
The inventors of the present application have proposed in Japanese Utility Model Application No. 105720/1987 (filed on July 9, 1987) a magnetic tape cassette wherein a member for restricting the position of a pad, which is formed integrally with the casing, is disposed at the rear side of a side wall of the casing so as to be interposed between the pad and an area of rotation of a reel hub. However, it is not always possible to dispose the pad position restricting member at such position because a certain type of casing has no sufficient space to accommodate the pad position restricting member at the rear side of the side wall of the casing and between the pad and the area of rotation of the reel hub.